Vigorous and hazardous manual labor is required to maneuver pipe sections or other generally cylindrical object to an unload position near the end of a trailer. Pipe sections, typically constructed of concrete and having a diameter up to twenty four inches, are commonly stacked in two horizontal rows with one on top of the other. One trailer-load of twelve-inch diameter pipe could consist of fifty pipe sections.
To move a pipe section from the top row to the surface of the trailer (i.e., the “deck”), the operator currently uses a bar to roll the rear pipe section from under the upper pipe section. As the upper pipe section nears the deck it will drop rapidly and could be damaged if the rear pipe section is not properly restrained. The operator must then re-block the pipe sections remaining on the trailer before rolling the removed pipe section the length of the trailer to an unload position at the rear end of the trailer.
Most trailers are arranged so that the deck slopes approximately six inches front to rear. Depending on the grade of the terrain, the operator may be required to restrain or push the pipe sections. Using a bar to move a large pipe section up a grade for any length is physically taxing, potentially dangerous, and time consuming. Restraining a pipe section from traversing down a grade requires the operator to place himself in front of the pipe section to hold or block it, which places the operator in a highly dangerous situation.
Once the pipe section is unloaded from the trailer and resting on the ground, the operator must position blocks adjacent that pipe section to prevent the next unloaded pipe section from colliding with that pipe section and causing damage. When done correctly, the operator places blocks after a pipe section is unloaded. However, many pipe sections are constructed with a bell on one end. This causes the pipe section to roll in an arc on the ground rather than in a straight line, which makes it difficult to judge where the next pipe section will contact the pipe sections already placed on the ground. Such difficulty gives rise to a very hazardous practice of the operator placing himself in the path of a rolling pipe section to place the block just before the point of impact with any pipe section already placed on the ground.
After the pipe section is unloaded, the operator walks from the area on the ground where he was blocking the pipe section and toward the trailer to unload the next pipe section. Many times this distance is fifty feet or more. Furthermore, after unloading two to five pipe sections, the operator must return to the cab of the truck and pull the trailer forward to allow room for more pipe sections. Improper blocking of pipe sections or entirely neglecting to block a pipe section has been a source of many accidents. Pipe sections freely traversing down a grade creates a very dangerous situation.